Weddell seals do not lengthen calls in response to conspecific masking

A preliminary study suggested that Weddell seals (Leptonychotes weddellii) increase the durations of some underwater call types when overlapped by another calling seal. The present study examined the durations and overlapping sequences of Weddell seal calls recorded in Eastern Antarctica.

The calling rate, call type (13 major categories), total duration, numbers of elements per call, and overlapping order of 100-200 consecutive calls per recording location were measured. In response to increased conspecific calling rates, the call durations and numbers of elements (within repeated-element call types) did not change or became shorter. Calls that were not overlapped were 3.8 plus or minus 6.1 s long, the first call in a series of overlapped calls was 14.4 plus or minus 15.7 s and subsequent calls in an overlapping series were 6.5 plus or minus 10.3 s.